Friction stir spot welding (FSSW) is a solid-state welding technique that creates a spot weld without melting the work pieces. In an FSSW process, a rotating tool with a contoured tip is plunged against two or more work pieces, such as flat sheet metal pieces, such that the resulting friction joins the work pieces together. During this process, the tip of the rotating tool penetrates through the top work piece and enters into the lower work piece. As the tip of the rotating tool exits the faying surface of the top work piece and enters the faying surface of the lower work piece, the rotating tool can cause the upper work piece to lift off of and undesirably deflect away from the lower work piece.